BACKGROUND: Acupuncture has been shown to be effective for the treatment of chronic musculoskeletal back, neck, and osteoarthritis pain. However, access to acupuncture treatment has been limited in medically underserved and low-income populations. OBJECTIVE: Acupuncture therapy delivered in groups could reduce cost and expand access. We compared the effectiveness of group versus individual acupuncture for pain and function among ethnically diverse, low-income primary care patients with chronic musculoskeletal pain. DESIGN: This was a randomized comparative effectiveness non-inferiority trial in 6 Bronx primary care community health centers. Participants with chronic ( > 3 months) back, neck, or osteoarthritis pain were randomly assigned to individual or group acupuncture therapy for 12 weeks. PARTICIPANTS: Seven hundred seventy-nine participants were randomized. Mean age was 54.8 years. 35.3% of participants identified as black and 56.9% identified as Latino. Seventy-six percent were Medicaid insured, 60% reported poor/fair health, and 37% were unable to work due to disability. INTERVENTIONS: Participants received weekly acupuncture treatment in either group or individual setting for 12 weeks. MAIN MEASURES: Primary outcome was pain interference on the Brief Pain Inventory at 12 weeks; secondary outcomes were pain severity (BPI), physical and mental well-being (PROMIS-10), and opiate use. Outcome measures were collected at baseline, 12 and 24 weeks. KEY RESULTS: 37.5% of individual arm and 30.3% in group had > 30% improvement in pain interference (d = 7.2%, 95% CI - 0.6%, 15.1%). Non-inferiority of group acupuncture was not demonstrated for the primary outcome assuming a margin of 10%. In the responder analysis of physical well-being, 63.1% of individual participants and 59.5% of group had clinically important improvement at 12 weeks (d = 3.6%, 95% CI - 4.2%, 11.4%). CONCLUSIONS: Both individual and group acupuncture therapy delivered in primary care settings reduced chronic pain and improved physical function at 12 weeks; non-inferiority of group was not shown. TRIAL REGISTRATION: Clinicaltrials.gov # NCT02456727.